People have faith in the ability of polygraph machines (more commonly known as lie detectors) to help police find the truth in criminal investigations. In reality, most polygraph tests are done for government security screenings, even though this has been outlawed in the private sector. According to a report from National Academy of Sciences, that's the most unreliable use for them.

The Boston Globe has a lengthy article about their history, their use, and some of the lives that have been damaged:

For nearly a century, almost everything about the polygraph has remained virtually unchanged. Its basic principle, that there are recordable physiological reactions that can indicate to a trained examiner when a person is being deceptive, is the same. The criticism of the machine has been as consistent through the years as its fundamental mechanics. Its proponents from the beginning have believed in it with a faith that is almost evangelical, and for nearly as long, its detractors have derided it as the worst kind of junk science and have seen that faith as having been the problem all along.

“The polygraph is the translation of a mythological device into a technological idiom,” says Steven Aftergood, the director of the Project on Government Secrecy for the Federation of American Scientists. “It does measure physiological changes like respiration and heartbeat and perspiration, but there’s no guaranteed nexus between those physiological changes and truth-telling. In short, what the polygraph measures is not truth and deception but perspiration and respiration.” [..]

“Why do we keep using it when we keep saying it’s not reliable?” asks [New Mexico senator Jeff] Bingaman. “That’s an awfully good question. I think it just appeals to a lot of people’s faith that there’s a technological fix to every problem and, if you just get the right machine hooked up, you can determine all the right answers.”

Polygraphs are bunk — but they are very appealing to those in power, perhaps because they provide a veneer of scientific respectability to the process of weeding out good from bad candidates for a job. Instead of using their personal judgment, which might later be challenged as involving some sort of prejudice, they shift responsibility to an unreliable machine being used by a person who is likely using their own judgment. It looks scientific, but it's as valid as palm reading.

 

Quick Poll: Do you trust polygraph machines enough to submit to one for a job interview?

1. I don't trust them and wouldn't submit to one.
2. I don't trust them, but would submit if that's the only viable option.
3. I trust them and would submit to one without question.
4. I don't know / don't care.

Click an option to vote, or View Current Poll Results

 

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